This invention relates to apparatus and methods for determining the expiration date of medications and other compounds.
Over-the-counter (OTC) medications and many prescription medications are distributed to patients in containers that are labeled with an expiration date. Most consumers are familiar with the xe2x80x9cuse byxe2x80x9d or xe2x80x9cexpires onxe2x80x9d language used by pharmaceutical manufacturers to alert consumers of the date after which the medication should not be used. Although there are several different criteria for determining what constitutes a medication""s expiration date, the date printed on a label typically takes into account the fact that over time, active ingredients in medications can lose much of their potency. The expiration date of a medication is thus a measure of the therapeutic potency and effectiveness of the medication. The inclusion of an expiration date on a label thus provides important information to consumers, since the consumer is readily able to determine whether the medication should be used. Expiration information is needed for OTC drugs, which may remain on a consumer""s shelf for an extended period of time, and also on prescription drugs that may be retained by a patient after a treatment regime is completed or that may lose some potency during a treatment regime.
The expiration date of a medication is often determined by the pharmaceutical manufacturer using statistical methodology that takes into account predicted environmental conditions to which the drug will be exposed. Many environmental conditions have an impact on pharmacologically active compounds; in practice the primary environmental condition that impacts the therapeutic effectiveness of a medication is the temperature to which the medication is exposed. Normally, a higher temperature causes more rapid degradation of active ingredients contained in medication, and therefore a more rapid degradation of the medication""s therapeutic effectiveness. Conversely, most medications have a longer therapeutically effective life when stored at lower temperatures. As such, and because a manufacturer has no way of knowing, predicting or controlling the actual temperatures to which a medication will be exposed, the expiration dates printed on labels are predictions based on statistically expected ambient temperature conditions. Expiration dates typically are conservatively predicted using such statistical models to ensure that patients use effective medications.
Once a medication leaves the manufacturing facility there are few opportunities for the manufacturer to control storage conditions. This is especially true of OTC medications that are distributed and sold through retail channels. Since a medication will rarely be exposed to the ambient temperature conditions that are used in statistical models used to predict shelf life, the actual therapeutically effective life of a medication will rarely be the same as the predicted expiration date that is printed on a label. Stated otherwise, in most cases the actual time that a medication is therapeutically effective is either greater than the predicted expiration date (if the medication is actually stored at relatively low temperatures), or less than the predicted date (if stored at relatively higher temperatures). The result is that medications are either thrown out earlier than they should be, or worse, are consumed later than they should be and when they might have reduced potency and effectiveness.
The illustrated embodiment comprises apparatus for determining the expiration date of a medication supplied in a container. A temperature sensor measures the temperature of the medication over time, which is measured by a real time clock circuit. Temperature data and temperature exposure over time is compared to predetermined medication temperature profile data specific to the medication to generate an expiration date of the medication.